code: def test_max_pair_distance_pairs():
      """Test that max pair distance pairs are computed properly."""
      from rdkit import Chem
  
      # Carbon
      mol = Chem.MolFromSmiles("C")
      # Test distance 1
      pair_edges = max_pair_distance_pairs(mol, 1)
      assert pair_edges.shape == (2, 1)
      assert np.all(pair_edges.flatten() == np.array([0, 0]))
      # Test distance 2
      pair_edges = max_pair_distance_pairs(mol, 2)
      assert pair_edges.shape == (2, 1)
      assert np.all(pair_edges.flatten() == np.array([0, 0]))
  
      # Test alkane
      mol = Chem.MolFromSmiles("CCC")
      # Test distance 1
      pair_edges = max_pair_distance_pairs(mol, 1)
      # 3 self connections and 2 bonds which are both counted twice because of
      # symmetry for 7 total
      assert pair_edges.shape == (2, 7)
      # Test distance 2
      pair_edges = max_pair_distance_pairs(mol, 2)
      # Everything is connected at this distance
      assert pair_edges.shape == (2, 9)
  
file_path: deepchem/deepchem/feat/tests/test_weave.py
imports: import numpy
  import deepchem
  from deepchem.feat.graph_features import max_pair_distance_pairs
label_desc: Use image node_id 1 for calling a global function with example usage: test_max_pair_distance_pairs() without return types